Based on a classified value for the bias, Reagan administration officials have repeatedly said that Soviet nuclear testing activities for a number of tests constitute a likely violation of the TTBT -- that about 10 explosions each have had yields probably exceeding 150 KT.
Sykes estimates that if the Soviets were to violate the TTBT with a 300 KT test (which is thought to be militarily significant), and given a 41 percent uncertainty in yield, there would be an 84 percent chance that the U.
Some of the uncertainty about yield estimates could be reduced if the provisions of the TTBT and PNET, involving the exchange of information on tests and geology, were carried out (see box).
The TTBT banned underground nuclear weapon tests having a yield greater than 150 kilotons; the PNET extended this limit to peaceful nuclear explosions to preclude weapon tests under the guise of explosions for peaceful purposes.
President Carter pursued a CTBT rather than seeking Senate advice and consent to ratification of the TTBT and PNET.
Negotiations began on the verification protocols for the TTBT and PNET in November 1987; (228) as noted, these treaties had been signed in 1974 and 1976, respectively.